Earth Boss : Material :Body-Mild Steel, Fittings - Stainless Steel The earth boss is designed to provide an earth point on a steel structure.The boss is welded into place. Cast Ground Plate or Earth Plate : These Plates when used in concrete structures offer convenient ground system connection points. They are used where reinforcing bars are electrically continous & are to be used as donw conductors. These earth points allow easy acces for the lightning protection & earhting system. Hole ThreadLWProduct Code 10 50 50 HPB 01 Drwg. No.Cond. SizeHoleProduct Code A 120 2 Hole HCCP - 2120 B 120 4 Hole HCCP - 4120 B 240 4 Hole HCCP - 4240 C 240 4 Hole HCCPL - 4240